The exact role gastrointestinal (GI) peptides play in the control of nutrient assimilation remains undetermined. The area is complicated by the multitude of peptides known with regulatory functions and diversity of effects on secretion, absorption, motility, blood flow and tissue growth. They may act as endocrines, paracrines, autocrines, neurotransmitters or neuromodulators. These diverse effects and the ubiquitous distribution suggests they function as complex regulatory peptides. Peptides influence tissue growth and development as well as immediate cell responses such as secretion. An understanding of the roles of regulatory peptides requires consideration of all these processes. The field of GI hormone physiology thus incorporates scientists from diverse disciplines, including cell and molecular biologists, endocrinologist, gastroenterologists, neurologists, immunologists, animal physiologists and clinical scientists. This symposium is designed to: 1) bring. together these various disciplines to raise consciousness of diverse mechanisms involved in peptide action, 2) disseminate new information of peptides' roles in the developing GI tract, 3) foster collaborative research for furthering understanding and treatment of GI diseases and 4) interest young investigators in this field. The symposium is a 2 1/2 day meeting- The 1st morning is devoted to peptide regulation of intestinal development including discussions of the most recent knowledge of GI peptide's effects on the development of neonatal intestine. The 2nd session centers on growth factors, receptors, signal transduction in both G-Protein and the Tyrosine Kinase receptor families and growth factor regulation of gene expression. The second day will be devoted to peptide effects on neuromodulation of intestinal function and the development/regulation of the mucosal immune system. The third day will be devoted to neuropeptide therapy in clinical situations. In addition to these platform sessions, there is a poster session to allow participants to present results of the most recent studies in this area for additional discussion and scientific review.